Conventionally, a stent has been used in the percutaneous transluminal coronary angioplasty (PTCA), for example, to prevent a stenosis portion of the coronary artery from restenosis due to recoil or the like after dilation with a balloon. The stent has a peripheral wall portion in an approximate shape of a cylinder, for example, and this peripheral wall portion is composed of a line-shaped body that extends in a helical form in the circumferential direction while reciprocating in the axial direction at a given amplitude. Then, the stent inserted into the somatic lumen such as the coronary artery under a constricted condition in the radial direction is expanded in the radial direction with a balloon or by self-expansion using the shape-memory effect of the stent itself to be implanted in close contact with the inner wall surface of the somatic lumen. This prevents restenosis caused by recoiling and the like due to the stent's rigidity in the radial direction, thus maintaining the inner diameter of the somatic lumen in a state of being expanded with a balloon.
Meanwhile, in the stent formed by coiling the line-shaped body in a helical form, since the portions adjacent to each other in the axial direction are not positioned against each other allowing them to move freely in the axial direction, there is a risk of not expanding uniformly due to the density disparity in the arrangement of the line-shaped body when the stent is expanded in the radial direction with a balloon and the like. Therefore, in Japanese Domestic Publication of International Patent Application No. JP-A-2011-502636 (Patent Document 1) proposes a structure where a connecting part (connector 30) is provided to link the adjacent portions of the line-shaped body to each other in the axial direction. This allows the rigidity of the stent in the longitudinal direction to be enhanced to achieve configuration stability.
However, once the line-shaped body is linked by the connecting part in the axial direction, the stent's rigidity not only in the longitudinal direction but also in the radial direction is increased so that its conformability to the bend of the somatic lumen and the like is degraded. As a result, there was a risk of encountering stent fracture caused by the stent remaining in the bent portion for a long time to be charged with repeated loads of blood flow and the like, which caused a problem such as a higher rate of restenosis of the somatic lumen. In addition, as the stent's rigidity increases, the stent remaining in place gets less susceptible to deformation in conformity to the configuration of the somatic lumen, which poses another risk of damaging the body tissues such as those of blood-vessel walls by pressing the tip end of the stent against them.